An Evaluation of Heat Strain Monitoring Methods for Workers in Encapsulating, Impermeable Protective Clothing
COAST GUARD WASHINGTON DC OFFICE OF RESEARCH AND DEVELOPMENT
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Heat strain for six young, healthy, acclimized men mean age 26.2 yrs., weight 84.1 kg was measured during moderate exercise at various ambient conditions 21.5 C, 28 C, 31.5 C with sunshine while wearing fully encapsulating chemical protective suits with self-contained breathing apparatus. The total weight of the Coast Guard Chemical Response Suit was 26.3 kg. The subjects performed a total of 35 minutes 20 minutes exercise, as determined by VO2 measurements was 383 Kcalhr. Heart rate and mean skin temperature rose significantly as ambient temperature increased. Under the most adverse ambient condition 31.5 C with sunshine, the mean heart rate and skin temperature were elevated 39.6 bpm and 4.1 C, respectively, over those recorded for control conditions. Significant increases in rectal temperature were not noted. A mean difference in weight loss was only observed with significance between control conditions and the most severe ambient environment. The five minute recovery heart rate, recorded at minute 25 after 20 minutes of exercise, increased significantly as ambient temperature conditions became more adverse. It is concluded that wearers of impermeable protective clothing show progressive increases in heat strain as ambient temperature increases. This study indicates that recovery heart rate is probably the best indicator of heat tolerance endpoints for work in encapsulating, impermeable protective clothing.
- Stress Physiology